Transient Electromyographic Responses by Isokinetic Torque Release during Mechanically Assisted Elbow Flexion.

Power assistance on joint torque may not be beneficial to all the related muscles. We investigated the effects of power assistance on torque release during isokinetic elbow flexion. An isokinetic dynamometer system was used to simulate dynamic elbow flexion with power assistance, which altered the exercise conditions of baseline isometric torque (greater and lower) and rotation speed (faster and slower) of the lever arm. Ten male right-handed participants performed exercise tasks using the system. We measured (1) the electromyogram (EMG) amplitudes of the biceps brachii (BB), brachioradialis (BR), and triceps brachii (TB) muscles, (2) torque output and its variability, and (3) the perceived assistance level. Transient responses of the objective measurements were analyzed by observing three time epochs before and after power assistance. Greater variability and lower perceived assistance levels were observed when greater torque was released at a faster rotation speed. The torque output and EMG amplitudes of BB and BR muscles decreased over time. However, EMG amplitudes in the TB muscle were relatively constant until 200 ms after power assistance resulting in greater muscle co-contraction. This could be attributed to the increased postural stability of the human musculature system when the external perturbation on joint movement occurred by power assistance, independent of exercise conditions.

The effects of umbrella handle shape and grip type on muscle activation and postural variability under windy conditions.

This study investigated how different shapes of umbrella handles and grip types influence muscle activation and postural variability under windy conditions. Seventeen adult participants were enrolled in this study, and different handle shapes (cylindrical, ellipsoidal, and triangular prism-shaped), grip types (four- and five-finger grip), and wind strengths were tested. Activation of the forearm and upper arm muscles was recorded using surface electromyography. Postural variability and ratings of (1) perceived difficulty of use and (2) perceived grip-posture variability were measured. The results indicated that activation of the finger flexor muscle increased under windy conditions, whereas postural variability was not affected. Weak wind (3.2-7.5 m/s) conditions caused greater perceived postural variability and activation of the wrist extensor muscle. The ellipsoidal handle shape had lower endpoint postural variability when held with a five-finger grip and also had lower perceived postural variability and difficulty compared to that with the cylindrical shape. Our findings can be used to select appropriate umbrella handle designs based on grip type and wind conditions.

Description of Luteibacter aegosomatis sp. nov., Luteibacter aegosomaticola sp. nov., and Luteibacter aegosomatissinici sp. nov. isolated from the Intestines of Aegosoma sinicum Larvae.

Three novel bacterial strains, 321T, 335T, and 353T, were isolated from the intestines of Aegosoma sinicum larvae collected from Paju-Si, South Korea. The strains were Gram-negative, obligate aerobe and had rod-shaped cells with a single flagellum. The three strains belonged to the genus Luteibacter in the family Rhodanobacteraceae and shared < 99.2% similarity in their 16S rRNA gene sequence and < 83.56% similarity in thier whole genome sequence. Strains 321T, 335T, and 353T formed a monophyletic clade with Luteibacter yeojuensis KACC 11405T, L. anthropi KACC 17855T, and L. rhizovicinus KACC 12830T, with sequence similarities of 98.77-98.91%, 98.44-98.58%, and 97.88-98.02%, respectively. Further genomic analyses, including the construction of the Up-to-date Bacterial Core Gene (UBCG) tree and assessment of other genome-related indices, indicated that these strains were novel species belonging to the genus Luteibacter. All three strains contained ubiquinone Q8 as their major isoprenoid quinone and iso-C15:0 and summed feature 9 (C16:0 10-methyl and/or iso-C17:1 ω9c) as their major cellular fatty acids. Phosphatidylethanolamine and diphosphatidylglycerol were the major polar lipids in all the strains. The genomic DNA G + C contents of strains 321T, 335T, and 353T were 66.0, 64.5, and 64.5 mol%, respectively. Based on multiphasic classification, strains 321T, 335T, and 353T were classified into the genus Luteibacter as the type strains of novel species, for which the names Luteibacter aegosomatis sp. nov., Luteibacter aegosomaticola sp. nov., and Luteibacter aegosomatissinici sp. nov. are proposed, respectively.

Impact of task variation and microbreaks on muscle fatigue at seated and standing postures.

BACKGROUND: Prolonged and sustained work posture among computer users is one of the main factors that contributes to musculoskeletal discomfort. Rest-break interventions such as task variation and microbreaks may help prevent muscle fatigue and work-related musculoskeletal disorder. OBJECTIVE: We aimed to investigate the effects of task variation and microbreaks at seated and standing workstations on forearm muscle activity, namely extensor digitorum communis, extensor carpi ulnaris, flexor digitorum superficialis, and flexor carpi ulnaris; mouse operation force (vertical compression force); mouse operation parameters; and perceived body discomfort during mouse operation. METHODS: Twelve healthy right-handed young adults were recruited (male: n = 7, 21.6±1.4 years; female: n = 5, 21.4±1.7 years). Participants performed three blocks of computer tasks (computer mouse operation and typing) in both seated and standing postures with each block lasting for 30 min. Surface electromyography (EMG) of the forearm muscles and operation force were monitored during computer mouse operation. Body discomfort rating was recorded at the end of each block. RESULTS: With simulated task variation and microbreaks, work posture and work time showed no significant difference with EMG amplitude and mouse operation force. CONCLUSION: Task variation and microbreaks could be of benefit to computer users by reducing muscle fatigue during long hours of computer work at both seated and standing workstations.

Users' adaptations to the proportional speed control of a motorised walker.

PURPOSE: Speed control is commonly used to regulate the forces applied by motorised walkers (MW) and there are often situations where the speed targeted deviates from the preferred walking speed of its users, such as when encouraging higher walking speeds and due to safety consideration. This study investigates the effects of different MW's target speeds on the selected walking speeds, force applied, perceived exertion, and gait of MW users during steady-state walking. MATERIALS AND METHODS: The spatiotemporal gait parameters and perceived exertion of twenty young healthy participants were measured as they walked at a comfortable, self-selected speed using a MW as it was controlled to target forward speeds of 0.6, 0.8, 1.0, 1.2, and 1.4 m s-1 as well as when no assistive force was applied by the MW. RESULTS: On average, users would walk slower when their "No Assist" walking speed is higher than the MW's speed target and vice versa. Additionally, the force applied to the MW is proportional to the difference in speed, either faster or slower, when compared to "No Assist". CONCLUSION: The user's exertion and the energy used by the MW are both minimised when target speed is close to the preferred walking speed of the user. Additionally, these findings suggest that the speed target can be used to change the walking speed of users but only to a certain extend and at the cost of higher perceived exertion.Implications for rehabilitationThe larger the difference between the target speed of the MW and the preferred walking speed of the user, the more likely the user is to push or pull on the MW.Users would push or pull on the MW with a force proportional to the difference from their preferred walking speed even when matching the MW's target speed.Users can be encouraged to walk at higher than preferred speeds, even though this would come at the cost of higher perceived exertion.

Parasphingorhabdus cellanae sp. nov., isolated from the gut of a Korean limpet, Cellana toreuma.

A novel bacterium, designated strain JHSY0214T, was isolated from the gut of a Korean limpet, Cellana toreuma. Cells of strain JHSY0214T were Gram-stain-negative, strictly aerobic, yellow-pigmented, non-spore-forming, non-motile and showed a rod-coccus growth cycle. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain belonged to the genus Parasphingorhabdus, and was most closely related to Parasphingorhabdus litoris KCTC 12764T (98.71 %). Strain JHSY0214T had two fluoroquinolone-resistance genes and seven multidrug-resistance efflux pump genes, but did not have beta-lactamase genes and zinc resistance genes compared with P. litoris KCTC 12764T. Strain JHSY0214T grew optimally at 30 °C, pH 7.0 and in the presence of 2 % (w/v) NaCl. The predominant cellular fatty acids of strain JHSY0214T were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c; 41.2 %), summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c; 21 %) and C16 : 0 (18.9 %). The major isoprenoid quinone was ubiquinone-10. The major polar lipids were sphingoglycolipid and phosphatidylethanolamine. The genomic DNA G+C content was 52.8 mol%. Based on phylogenetic, genotypic and phenotypic data, strain JHSY0214T represents a novel species of the genus Parasphingorhabdus, for which the name Parasphingorhabdus cellanae is proposed. The type strain is JHSY0214T (=KCTC 82387T=DSM 112279T).

The Effects of Standing Working Posture on Operation Force and Upper Limb Muscle Activation When Using Different Pointing Devices.

This study investigated how sitting and standing working postures affected operation force, upper limb muscle activation, and task performance using different pointing devices. Fifteen male participants completed cursor aiming and dragging tasks using a conventional mouse, a vertical mouse, and a trackball at sitting and standing workstations. A custom-made force plate was used to measure operation forces applied to the pointing devices. Surface electromyography (EMG) was used to capture the activation of the biceps brachii, triceps brachii, deltoid, and trapezius. Task performance was measured by task success rates, and subjective ratings were obtained for the force required for operation, smoothness of operation, accuracy, and local fatigue in the upper limb. We quantified the following significant outcomes: (1) greater operation forces were found when standing; (2) standing reduced EMG amplitudes of the triceps and trapezius muscles for all tasks; (3) during the aiming task, the vertical mouse had greater operation forces; (4) during the dragging task, both the vertical mouse and trackball had greater operation forces; and (5) task success rates differed for pointing devices only when sitting. This study revealed the distinct biomechanical properties of standing working posture and suggested limited beneficial effects of alternative pointing devices in terms of task performance and subjective ratings.

Arginine-mediated gut microbiome remodeling promotes host pulmonary immune defense against nontuberculous mycobacterial infection.

Nontuberculous mycobacterial pulmonary diseases (NTM-PDs) are emerging as global health threats with issues of antibiotic resistance. Accumulating evidence suggests that the gut-lung axis may provide novel candidates for host-directed therapeutics against various infectious diseases. However, little is known about the gut-lung axis in the context of host protective immunity to identify new therapeutics for NTM-PDs. This study was performed to identify gut microbes and metabolites capable of conferring pulmonary immunity to NTM-PDs. Using metabolomics analysis of sera from NTM-PD patients and mouse models, we showed that the levels of l-arginine were decreased in sera from NTM-PD patients and NTM-infected mice. Oral administration of l-arginine significantly enhanced pulmonary antimicrobial activities with the expansion of IFN-γ-producing effector T cells and a shift to microbicidal (M1) macrophages in the lungs of NTM-PD model mice. Mice that received fecal microbiota transplants from l-arginine-treated mice showed increased protective host defense in the lungs against NTM-PD, whereas l-arginine-induced pulmonary host defense was attenuated in mice treated with antibiotics. Using 16S rRNA sequencing, we further showed that l-arginine administration resulted in enrichment of the gut microbiota composition with Bifidobacterium species. Notably, oral treatment with either Bifidobacterium pseudolongum or inosine enhanced antimicrobial pulmonary immune defense against NTM infection, even with multidrug-resistant clinical NTM strains. Our findings indicate that l-arginine-induced gut microbiota remodeling with enrichment of B. pseudolongum boosts pulmonary immune defense against NTM infection by driving the protective gut-lung axis in vivo.

Description of Polaribacter batillariae sp. nov., Polaribacter cellanae sp. nov., and Polaribacter pectinis sp. nov., novel bacteria isolated from the gut of three types of South Korean shellfish.

Three aerobic, Gram-negative, and rod-shaped bacterial strains, designated strains G4M1T, SM13T, and L12M9T, were isolated from the gut of Batillaria multiformis, Cellana toreuma, and Patinopecten yessoensis collected from the Yellow Sea in South Korea. All the strains grew optimally at 25°C, in the presence of 2% (w/v) NaCl, and at pH 7. These three strains, which belonged to the genus Polaribacter in the family Flavobacteriaceae, shared < 98.8% in 16S rRNA gene sequence and < 86.68% in whole-genome sequence with each other. Compared with the type strains of Polaribacter, isolates showed the highest sequence similarity to P. haliotis KCTC 52418T (< 98.68%), followed by P. litorisediminis KCTC 52500T (< 98.13%). All the strains contained MK-6 as their predominant menaquinone and iso-C15:0 as their major fatty acid. Moreover, all the strains had phosphatidylethanolamine as their polar lipid component. In addition, strain G4M1T had two unidentified lipids and three unidentified aminolipids, strain SM13T had three unidentified lipids and three unidentified aminolipids, and strain L12M9T had three unidentified lipids and one unidentified aminolipid. The DNA G + C contents of strains G4M1T, SM13T, and L12M9T were 31.0, 30.4, and 29.7 mol%, respectively. Based on phenotypic, phylogenetic, chemotaxonomic, and genotypic findings, strains G4M1T (= KCTC 82388T = DSM 112372T), SM13T (= KCTC 82389T = DSM 112373T), and L12M9T (= KCTC 62751T = DSM 112374T) were classified into the genus Polaribacter as the type strains of novel species, for which the names Polaribacter batillariae sp. nov., Polaribacter cellanae sp. nov., and Polaribacter pectinis sp. nov., respectively, have been proposed.

Different flooring surfaces affect infants' crawling performance.

This study assessed the influence of different types of flooring on infants' crawling motion patterns and performance. Each participating infant (range: 8.7-12.4 months) was encouraged to crawl on a tatami mat made of woven straw as well as other flooring types such as hardwood, carpet, and joint mat. Material tests were conducted to quantify the friction and shock absorption of the flooring. A three-dimensional motion capture system was used to measure spatiotemporal and kinematic variables during hands-and-knees crawling. An increased crawling rate was associated with a faster cadence of cyclic arm movements, but not with crawling stride length. Hardwood flooring had a significantly lower crawling rate and longer duration of hand-floor contact than tatami, while the crawling stride length and range of motion of joint movements were hardly affected by flooring type. The results of this study suggest a drawback of hardwood flooring in terms of infants' effective quadrupedal locomotion.

The effect of horizontal forces from a Smart Walker on gait and perceived exertion.

Increasingly, electric motors are being incorporated into wheeled walkers to implement various smart features to better assist their users physically. These modified walkers, known as Smart Walkers, use their electric motors to generate horizontal forces that can be used to reduce the physical load for walking, prevent falls and provide navigation support. However, these forces can also alter gait and may inadvertently increase the exertion of the users. This study aims to describe the effects of assistive and resistive horizontal forces (from -18.47 N to 27.70 N) from a Smart Walker on gait and perceived exertion of its users during steady-state walking. Self-selected comfortable walking speed, cadence, stride length, double support phase and ratings of perceived exertion (RPE) were significantly affected and different effects were found for resistive force, relatively low assistive force and high assistive force. With increasing force from -18.47 N to 0 N, RPE decreased and the users walked with lower double support time. From 0 N to 9.23 N, RPE continued to decrease to its lowest point while gait parameters remained constant. Further increasing force up to 27.70 N increased RPE and led to the users to choose to walk at higher speeds. This study demonstrates that users adapt their gait significantly to the forces applied and relatively high constant forces, whether assistive or resistive, will increase perceived exertion. Hence, these need to be carefully considered when developing Smart Walkers in order to provide safe and effective support to its users.

Chitinibacter bivalviorum sp. nov., isolated from the gut of the freshwater mussel Anodonta arcaeformis.

A novel Gram-stain-negative, aerobic, rod-shaped bacterium with a single polar flagellum, designated strain 2T18T, was isolated from the gut of the freshwater mussel Anodonta arcaeformis collected in the Republic of Korea. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain belonged to the genus Chitinibacter. Strain 2T18T formed a monophyletic clade with Chitinibacter fontanus KCTC 42982T, C. tainanensis KACC 11706T and C. alvei KCTC 23839T, with sequence similarities of 98.5, 98.4 and 95.9 %, respectively. Strain 2T18T exhibited optimal growth at 30 °C, at pH 8 and with 0.5 % (w/v) NaCl. The major isoprenoid quinone was ubiquinone-8 (Q-8). The predominant fatty acids were summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c) and C16 : 0. The polar lipids comprised phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified lipid, three unidentified phospholipids and two unidentified aminophospholipids. The G+C content of the genomic DNA was 50.6 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strains 2T18T and C. fontanus KCTC 42982T were below the thresholds used for the delineation of a novel species. Based on the phylogenetic, phenotypic, chemotaxonomic and genotypic characteristics, strain 2T18T represents a novel species of the genus Chitinibacter, for which the name Chitinibacter bivalviorum sp. nov. is proposed. The type strain is 2T18T (=KCTC 72821T=CCUG 74764T).

Brevilactibacter coleopterorum sp. nov., isolated from the intestine of the dark diving beetle Hydrophilus acuminatus, and Weissella coleopterorum sp. nov., isolated from the intestine of the diving beetle Cybister lewisianus.

A polyphasic taxonomic approach was used to characterize two novel bacterial strains, designated as HDW11T and HDW19T, isolated from intestine samples of the dark diving beetle Hydrophilus acuminatus and the diving beetle Cybister lewisianus, respectively. Both isolates were Gram-stain-positive, facultatively anaerobic and non-motile. Strain HDW11T grew optimally at 30 °C, pH 8 and in the presence of 1% (w/v) NaCl. Strain HDW19T grew optimally at 25 °C, pH 7 and in the presence of 0.3% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences and genome sequences revealed that strain HDW11T is a member of the genus Brevilactibacter and is closely related to Brevilactibacter flavus VG341T [with 97.9% 16S rRNA sequence identity and 79.1% average nucleotide identity (ANI)], and that strain HDW19T belongs to the genus Weissella and is closely related to W. koreensis KCTC 3621T (with 98.9% 16S rRNA sequence identity and 79.5% ANI). The major cellular fatty acids of strains HDW11T and HDW19T were C18:1 ω9c and anteiso-C15:0, respectively. The sole respiratory quinone of strain HDW11T was MK-9 (H4). The major polar lipid components of strain HDW11T were diphosphatidylglycerol and phosphatidylglycerol, and the major polar lipid component of strain HDW19T was diphosphatidylglycerol. The genomic DNA G+C content of strains HDW11T and HDW19T were 72.1 and 37.2 mol%, respectively. The results of phylogenetic, phenotypic, chemotaxonomic and genotypic analyses suggest that strain HDW11T represents a novel species within the genus Brevilactibacter, and that strain HDW19T represents a novel species within the genus Weissella. We propose the name Brevilactibacter coleopterorum sp. nov. for strain HDW11T (=KACC 21335T=KCTC 49320T=JCM 33680T) and the name Weissella coleopterorum for strain HDW19T (=KACC 21347T=KCTC 43114T=JCM 33684T).

Description of Nocardioides piscis sp. nov., Sphingomonas piscis sp. nov. and Sphingomonas sinipercae sp. nov., isolated from the intestine of fish species Odontobutis interrupta (Korean spotted sleeper) and Siniperca scherzeri (leopard mandarin fish).

A polyphasic taxonomic approach was used to characterize three novel bacterial strains, designated as HDW12AT, HDW-15BT, and HDW15CT, isolated from the intestine of fish species Odontobutis interrupta or Siniperca scherzeri. All isolates were obligate aerobic, non-motile bacteria, and grew optimally at 30°C. Phylogenetic analysis based on 16S rRNA sequences revealed that strain HDW12AT was a member of the genus Nocardioides, and closely related to Nocardioides allogilvus CFH 30205T (98.9% sequence identities). Furthermore, strains HDW15BT and HDW15CT were members of the genus Sphingomonas, and closely related to Sphingomonas lutea JS5T and Sphingomonas sediminicola Dae 20T (97.1% and 97.9% sequence identities), respectively. Strain HDW12AT contained MK-8 (H4), and strains HDW15BT and HDW15CT contained Q-10 as the respiratory quinone. Major polar lipid components of strain HDW12AT were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylinositol, and those of strains HDW15BT and HDW15CT were sphingoglycolipid, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and phosphatidylcholine. The G + C content of strains HDW12AT, HDW15BT, and HDW15CT were 69.7, 63.3, and 65.5%, respectively. The results of phylogenetic, phenotypic, chemotaxonomic, and genotypic analyses suggest that strain HDW12AT represents a novel species within the genus Nocardioides, and strains HDW15BT and HDW15CT represent two novel species within the genus Sphingomonas. We propose the names Nocardioides piscis for strain HDW12AT (= KACC 21336T = KCTC 49321T = JCM 33670T), Sphingomonas piscis for strain HDW15BT (= KACC 21341T = KCTC 72588T = JCM 33738T), and Sphingomonas sinipercae for strain HDW15CT (= KACC 21342T = KCTC 72589T = JCM 33739T).

Tessaracoccus coleopterorum sp. nov., isolated from the intestine of the dark diving beetle, Hydrophilus acuminatus.

A polyphasic taxonomic approach was used to characterize a novel bacterium, designated as strain HDW20T, isolated from the intestine of the dark diving beetle Hydrophilus acuminatus. The isolate was Gram-stain-positive, facultatively anaerobic, non-motile, coccus-shaped, and formed pale orange colonies. Phylogenetic analysis based on 16S rRNA gene sequences and genome sequences showed that the isolate belonged to the genus Tessaracoccus in the phylum Actinobacteria and was closely related to T. flavescens SST-39T, T. defluvii JCM 17540T, and T. aquimaris NSG39T, with the highest 16S rRNA gene sequence similarity of 98.5 % and a highest average nucleotide identity (ANI) value of 80.6 %. The major cellular fatty acids were C18 : 1 ω9c and anteiso-C15 : 0. The main respiratory quinone was MK-9 (H4). The major polar lipid components were phosphatidylglycerol and diphosphatidylglycerol. The genomic DNA G+C content was 69.0 %. The isolate contains ʟʟ-diaminopimelic acid, ʟ-alanine, and ʟ-lysine as amino acid components, and ribose, glucose, and galactose as sugar components of the cell wall peptidoglycan. The results of phylogenetic, phenotypic, chemotaxonomic, and genotypic analyses suggested that strain HDW20T represents a novel species within the genus Tessaracoccus. We propose the name Tessaracoccus coleopterorum sp. nov. The type strain is HDW20T (=KACC 21348T=KCTC 49324T=JCM 33674T).

Primary cilia mediate early life programming of adiposity through lysosomal regulation in the developing mouse hypothalamus.

Hypothalamic neurons including proopiomelanocortin (POMC)-producing neurons regulate body weights. The non-motile primary cilium is a critical sensory organelle on the cell surface. An association between ciliary defects and obesity has been suggested, but the underlying mechanisms are not fully understood. Here we show that inhibition of ciliogenesis in POMC-expressing developing hypothalamic neurons, by depleting ciliogenic genes IFT88 and KIF3A, leads to adulthood obesity in mice. In contrast, adult-onset ciliary dysgenesis in POMC neurons causes no significant change in adiposity. In developing POMC neurons, abnormal cilia formation disrupts axonal projections through impaired lysosomal protein degradation. Notably, maternal nutrition and postnatal leptin surge have a profound impact on ciliogenesis in the hypothalamus of neonatal mice; through these effects they critically modulate the organization of hypothalamic feeding circuits. Our findings reveal a mechanism of early life programming of adult adiposity, which is mediated by primary cilia in developing hypothalamic neurons.

Effects of mechanical assistance on muscle activity and motor performance during isometric elbow flexion.

Mechanical assistance on joint movement is generally beneficial; however, its effects on cooperative performance and muscle activity needs to be further explored. This study examined how motor performance and muscle activity are altered when mechanical assistance is provided during isometric force control of ramp-down and hold phases. Thirteen right-handed participants (age: 24.7 ± 1.8 years) performed trajectory tracking tasks. Participants were asked to maintain the reference magnitude of 47 N (REF) during isometric elbow flexion. The force was released to a step-down magnitude of either 75% REF or 50% REF and maintained, with and without mechanical assistance. The ramp-down durations of force release were set to 0.5, 2.5, or 5.0 s. Throughout the experiment, we measured the following: (1) the force output using load cells to compute force variability and overshoot ratio; (2) peak perturbation on the elbow movement using an accelerometer; (3) the surface electromyography (sEMG) from biceps brachii and triceps brachii muscles; and (4) EMG oscillation from the biceps brachii muscle in the bandwidth of 15-45 Hz. Our results indicated that mechanical assistance, which involved greater peak perturbation, demonstrated lower force variability than non-assistance (p < 0.01), while EMG oscillation in the biceps brachii muscle from 15 to 45 Hz was increased (p < 0.05). These findings imply that if assistive force is provided during isometric force control, the central nervous system actively tries to stabilize motor performance by controlling specific motor unit activity in the agonist muscle.

Force and electromyography responses during isometric force release of different rates and step-down magnitudes.

This study investigated motor responses of force release during isometric elbow flexion by comparing effects of different ramp durations and step-down magnitudes. Twelve right-handed participants (age: 23.1 ±â€¯1.1) performed trajectory tracking tasks. Participants were instructed to release their force from the reference magnitude (REF; 40% of maximal voluntary contraction force) to a step-down magnitude of 67% REF or 33% REF and maintain the released magnitude. Force release was guided by ramp durations of either 1 s or 5 s. Electromyography of the biceps brachii and triceps brachii was performed during the experimental task, and the co-contraction ratio was evaluated. Force output was recorded to evaluate the parameters of motor performance, such as force variability and overshoot ratio. Although a longer ramp duration of 5 s decreased the force variability and overshoot ratio than did shorter ramp duration of 1 s, higher perceived exertion and co-contraction ratio were followed. Force variability was greater when force was released to the step-down magnitude of 33% REF than that when the magnitude was 67% REF, however, the overshoot ratio showed opposite results. This study provided evidence proving that motor control strategies adopted for force release were affected by both duration and step-down magnitude. In particular, it implies that different control strategies are required according to the level of step-down magnitude with a relatively short ramp duration.

Spexin-Based Galanin Receptor Type 2 Agonist for Comorbid Mood Disorders and Abnormal Body Weight.

Despite the established comorbidity between mood disorders and abnormal eating behaviors, the underlying molecular mechanism and therapeutics remain to be resolved. Here, we show that a spexin-based galanin receptor type 2 agonist (SG2A) simultaneously normalized mood behaviors and body weight in corticosterone pellet-implanted (CORTI) mice, which are underweight and exhibit signs of anhedonia, increased anxiety, and depression. Administration of SG2A into the lateral ventricle produced antidepressive and anxiolytic effects in CORTI mice. Additionally, SG2A led to a recovery of body weight in CORTI mice while it induced significant weight loss in normal mice. In Pavlovian fear-conditioned mice, SG2A decreased contextual and auditory fear memory consolidation but accelerated the extinction of acquired fear memory without altering innate fear and recognition memory. The main action sites of SG2A in the brain may include serotonergic neurons in the dorsal raphe nucleus for mood control, and proopiomelanocortin/corticotropin-releasing hormone neurons in the hypothalamus for appetite and body weight control. Furthermore, intranasal administration of SG2A exerted the same anxiolytic and antidepressant-like effects and decreased food intake and body weight in a dose-dependent manner. Altogether, these results indicate that SG2A holds promise as a clinical treatment for patients with comorbid mood disorders and abnormal appetite/body weight.

Designing a Chatbot for a Brief Motivational Interview on Stress Management: Qualitative Case Study.

BACKGROUND: In addition to addiction and substance abuse, motivational interviewing (MI) is increasingly being integrated in treating other clinical issues such as mental health problems. Most of the many technological adaptations of MI, however, have focused on delivering the action-oriented treatment, leaving its relational component unexplored or vaguely described. This study intended to design a conversational sequence that considers both technical and relational components of MI for a mental health concern. OBJECTIVE: This case study aimed to design a conversational sequence for a brief motivational interview to be delivered by a Web-based text messaging application (chatbot) and to investigate its conversational experience with graduate students in their coping with stress. METHODS: A brief conversational sequence was designed with varied combinations of MI skills to follow the 4 processes of MI. A Web-based text messaging application, Bonobot, was built as a research prototype to deliver the sequence in a conversation. A total of 30 full-time graduate students who self-reported stress with regard to their school life were recruited for a survey of demographic information and perceived stress and a semistructured interview. Interviews were transcribed verbatim and analyzed by Braun and Clarke's thematic method. The themes that reflect the process of, impact of, and needs for the conversational experience are reported. RESULTS: Participants had a high level of perceived stress (mean 22.5 [SD 5.0]). Our findings included the following themes: Evocative Questions and Clichéd Feedback; Self-Reflection and Potential Consolation; and Need for Information and Contextualized Feedback. Participants particularly favored the relay of evocative questions but were less satisfied with the agent-generated reflective and affirming feedback that filled in-between. Discussing the idea of change was a good means of reflecting on themselves, and some of Bonobot's encouragements related to graduate school life were appreciated. Participants suggested the conversation provide informational support, as well as more contextualized feedback. CONCLUSIONS: A conversational sequence for a brief motivational interview was presented in this case study. Participant feedback suggests sequencing questions and MI-adherent statements can facilitate a conversation for stress management, which may encourage a chance of self-reflection. More diversified sequences, along with more contextualized feedback, should follow to offer a better conversational experience and to confirm any empirical effect.